/* global screenReaderText */
/**
 * Theme functions file.
 *
 * Contains handlers for navigation and widget area.
 */

( function( $ ) {
    var $body, $window, $sidebar, adminbarOffset, top = false,
        bottom = false, windowWidth, windowHeight, lastWindowPos = 0,
        topOffset = 0, bodyHeight, sidebarHeight, resizeTimer,
        secondary, button;

    function initMainNavigation( container ) {
        // Add dropdown toggle that display child menu items.
        container.find( '.menu-item-has-children > a' ).after( '<button class="dropdown-toggle" aria-expanded="false">' + screenReaderText.expand + '</button>' );

        // Toggle buttons and submenu items with active children menu items.
        container.find( '.current-menu-ancestor > button' ).addClass( 'toggle-on' );
        container.find( '.current-menu-ancestor > .sub-menu' ).addClass( 'toggled-on' );

        container.find( '.dropdown-toggle' ).click( function( e ) {
            var _this = $( this );
            e.preventDefault();
            _this.toggleClass( 'toggle-on' );
            _this.next( '.children, .sub-menu' ).toggleClass( 'toggled-on' );
            _this.attr( 'aria-expanded', _this.attr( 'aria-expanded' ) === 'false' ? 'true' : 'false' );
            _this.html( _this.html() === screenReaderText.expand ? screenReaderText.collapse : screenReaderText.expand );
        } );
    }
    initMainNavigation( $( '.main-navigation' ) );

    // Re-initialize the main navigation when it is updated, persisting any existing submenu expanded states.
    $( document ).on( 'customize-preview-menu-refreshed', function( e, params ) {
        if ( 'primary' === params.wpNavMenuArgs.theme_location ) {
            initMainNavigation( params.newContainer );

            // Re-sync expanded states from oldContainer.
            params.oldContainer.find( '.dropdown-toggle.toggle-on' ).each(function() {
                var containerId = $( this ).parent().prop( 'id' );
                $( params.newContainer ).find( '#' + containerId + ' > .dropdown-toggle' ).triggerHandler( 'click' );
            });
        }
    });

    secondary = $( '#secondary' );
    button = $( '.site-branding' ).find( '.secondary-toggle' );

    // Enable menu toggle for small screens.
    ( function() {
        var menu, widgets, social;
        if ( ! secondary.length || ! button.length ) {
            return;
        }

        // Hide button if there are no widgets and the menus are missing or empty.
        menu    = secondary.find( '.nav-menu' );
        widgets = secondary.find( '#widget-area' );
        social  = secondary.find( '#social-navigation' );
        if ( ! widgets.length && ! social.length && ( ! menu.length || ! menu.children().length ) ) {
            button.hide();
            return;
        }

        button.on( 'click.twentyfifteen', function() {
            secondary.toggleClass( 'toggled-on' );
            secondary.trigger( 'resize' );
            $( this ).toggleClass( 'toggled-on' );
            if ( $( this, secondary ).hasClass( 'toggled-on' ) ) {
                $( this ).attr( 'aria-expanded', 'true' );
                secondary.attr( 'aria-expanded', 'true' );
            } else {
                $( this ).attr( 'aria-expanded', 'false' );
                secondary.attr( 'aria-expanded', 'false' );
            }
        } );
    } )();

    /**
     * @summary Add or remove ARIA attributes.
     * Uses jQuery's width() function to determine the size of the window and add
     * the default ARIA attributes for the menu toggle if it's visible.
     * @since Twenty Fifteen 1.1
     */
    function onResizeARIA() {
        if ( 955 > $window.width() ) {
            button.attr( 'aria-expanded', 'false' );
            secondary.attr( 'aria-expanded', 'false' );
            button.attr( 'aria-controls', 'secondary' );
        } else {
            button.removeAttr( 'aria-expanded' );
            secondary.removeAttr( 'aria-expanded' );
            button.removeAttr( 'aria-controls' );
        }
    }

    // Sidebar scrolling.
    function resize() {
        windowWidth = $window.width();

        if ( 955 > windowWidth ) {
            top = bottom = false;
            $sidebar.removeAttr( 'style' );
        }
    }

    function scroll() {
        var windowPos = $window.scrollTop();

        if ( 955 > windowWidth ) {
            return;
        }

        sidebarHeight = $sidebar.height();
        windowHeight  = $window.height();
        bodyHeight    = $body.height();

        if ( sidebarHeight + adminbarOffset > windowHeight ) {
            if ( windowPos > lastWindowPos ) {
                if ( top ) {
                    top = false;
                    topOffset = ( $sidebar.offset().top > 0 ) ? $sidebar.offset().top - adminbarOffset : 0;
                    $sidebar.attr( 'style', 'top: ' + topOffset + 'px;' );
                } else if ( ! bottom && windowPos + windowHeight > sidebarHeight + $sidebar.offset().top && sidebarHeight + adminbarOffset < bodyHeight ) {
                    bottom = true;
                    $sidebar.attr( 'style', 'position: fixed; bottom: 0;' );
                }
            } else if ( windowPos < lastWindowPos ) {
                if ( bottom ) {
                    bottom = false;
                    topOffset = ( $sidebar.offset().top > 0 ) ? $sidebar.offset().top - adminbarOffset : 0;
                    $sidebar.attr( 'style', 'top: ' + topOffset + 'px;' );
                } else if ( ! top && windowPos + adminbarOffset < $sidebar.offset().top ) {
                    top = true;
                    $sidebar.attr( 'style', 'position: fixed;' );
                }
            } else {
                top = bottom = false;
                topOffset = ( $sidebar.offset().top > 0 ) ? $sidebar.offset().top - adminbarOffset : 0;
                $sidebar.attr( 'style', 'top: ' + topOffset + 'px;' );
            }
        } else if ( ! top ) {
            top = true;
            $sidebar.attr( 'style', 'position: fixed;' );
        }

        lastWindowPos = windowPos;
    }

    function resizeAndScroll() {
        resize();
        scroll();
    }

    $( document ).ready( function() {
        $body          = $( document.body );
        $window        = $( window );
        $sidebar       = $( '#sidebar' ).first();
        adminbarOffset = $body.is( '.admin-bar' ) ? $( '#wpadminbar' ).height() : 0;

        $window
            .on( 'scroll.twentyfifteen', scroll )
            .on( 'load.twentyfifteen', onResizeARIA )
            .on( 'resize.twentyfifteen', function() {
                clearTimeout( resizeTimer );
                resizeTimer = setTimeout( resizeAndScroll, 500 );
                onResizeARIA();
            } );
        $sidebar.on( 'click.twentyfifteen keydown.twentyfifteen', 'button', resizeAndScroll );

        resizeAndScroll();

        for ( var i = 1; i < 6; i++ ) {
            setTimeout( resizeAndScroll, 100 * i );
        }
    } );

} )( jQuery );
